A sheet supply tray and a sheet discharge tray are provided. Long sheets can be supplied from the sheet supply tray loaded with the long sheets. The sheet discharge tray is used also as the sheet supply tray, and receives the long sheets with a sheet discharge surface thereof in an area facing the sheet loading surface of the sheet supply tray. A discharge guide unit for guiding the discharge direction of the long sheets is detachably provided in such a dual-purpose type sheet discharge unit. A discharge/reception unit supporting the long sheets is detachably provided as a whole or a part of the sheet discharge unit. An extension sheet tray extensible with respect to a standard sheet tray is provided while the extension state of the extension sheet tray can be detected by an extension detection unit.